What are the disadvantages of high level languages?

Answer 1

Though it is much easier to code in a high level language, oftentimes access to more low-level functionalities are lost. For instance, the ability to communicate directly with the compiler and alter code before it gets transferred into machine code is lost. An example of this is the ability to optimize code in C, whereas the Java Compiler is a different deal altogether. Other abilities may include memory management, but mainly deal with behind-the-scenes architecture-related or runtime things.

Answer 2

In low level langauges like Assembly, you are working with the lowest possible chunks of code you can, machine code. The higher the level of a language, the more abstractions you use to organize ideas, and therefore, the less efficient it can become. For example, a regular integer in C or C++ on a 32bit system is simply 4 bytes. It can only represent a certain range of numbers, however. In the even higher level language of python, a number is an arbitrary number of bytes and can be as big as it needs to be, but a number in python is slightly bigger than the same number in C or C++ because it's structured differently.